It is known in the art that door assemblies, such as commercial and residential garage doors, rolling steel doors, and the like, for example, usually require counterbalancing mechanisms to counterbalance the weight of the door in order to decrease the force required to open the door and also facilitate its closing from a raised to a lowered position. Door assemblies may be manually or power operated, but in either case, particularly for manually operated doors, counterbalancing mechanisms have been used for many years to counterbalance the weight of the door and control its opening and closing movements so that one person can easily control the operation of the door. Counterbalancing mechanisms are also advantageous for power operated door assemblies since they reduce the power requirements needed for the motor and they lower the structural strength required for the opening and closing mechanism of the door. In other words, lighter weight, lower cost, door controlling mechanisms may be used if a counterbalancing mechanism is connected to the door to assist it in its opening and closing movements. Furthermore, the provision of a counterbalancing mechanism minimizes the chance of a rapid and uncontrolled closing of the door in the event of failure of one of the components of the door controlling mechanism, which can result in personal injury or damage to property.
It is also known in the art that a widely used type of counterbalancing mechanism 3, as used for a typical cable-operated door assembly such as the one illustrated in FIG. 1 for example, generally comprises a pair of spaced apart cable drums 5 connected to flexible cables 7, each cable 7 being in turn connected to a lower opposite side edge of the garage door 9. The cable drums 5 are usually mounted on an overhead shaft 11 which is supported above the door opening and is connected to one or more torsion springs 13 which are each fixed to the shaft 11 at one end, and secured to the wall at the other end, so that the cable drums 5 are biased to rotate in a direction which winds the cables 7 onto the drums and counteracts the weight of the door connected to the cables 7. Generally, conventional counterbalancing mechanisms 3 include two torsion springs 13 which are usually coaxially mounted onto the overhead shaft 11 and which are opposed to one another. Furthermore, the torsion springs 13 are adjusted by applying tension therein to properly balance the weight of the door 9 so that minimal opening and closing efforts are required, either manually or when motor controlled. The two drums 5 which are used for winding the cables 7 are usually fastened at each opposite end of the overhead shaft 11 and are fixed to the same by means of screws, whose respective ends are in contact with the shaft 11 and exert pressure thereon.
It is also known in the art that conventional, low cost adjustment devices used for the above-mentioned type of counterbalancing mechanisms, and widely utilized in the garage door industry and others, are generally cylindrical “collars” commonly referred to also as “plugs” 15 (or “cones”, “anchors”, etc.) which are connected to the so-called fixed ends of the torsion springs 13 and are mounted on the aforementioned shaft 11 for adjusting the deflection of the springs to preset the counterbalancing force. That is, each torsion spring 13 is usually coaxially mounted onto the overhead shaft 11 and is preferably connected with a stationary plug 15a at one end and a winding plug 15b at the other end. Usually, stationary plugs 15a are operatively connected to a fixed structure, such as for example, a support bracket 17 rigidly mounted to the wall. Moreover, winding plugs 15b are usually removably fixed to the overhead shaft 11 and are used to operatively connect the torsion spring 13 to the overhead shaft 11 so as to allow a torque transfer between the latter two. Hence, the above-mentioned plugs 15 ensure a mechanical connection between each opposite end of the torsional spring 13 and the support or a shaft, depending on whether they are respectively stationary plugs 15a or winding plugs 15b. The winding plugs 15b usually include one or more setscrews which lock the plugs to the shaft to prevent rotation therewith except during adjustment of the torsion spring. The winding plugs 15b also typically include sockets for receiving winding bars whereby the springs are often preset, or “preloaded”, manually, by rotating the winding plugs 15b with respect to the shaft 11 using the winding bars and then locking the winding plugs to the shaft 11 with the setscrews.
Thus, garage doors, rolling steel doors, mini-warehouse doors, and the like, as shown in FIG. 1, usually comprise counterbalancing mechanisms 3 to counterbalance the weight of the door 9 in order to decrease the force required to open such door 9 and also facilitate (e.g. control) its closing from a raised to a lowered position. As previously mentioned, in most counterbalancing mechanisms of most door assemblies, whether cable-operated or not, each torsion spring 13 is usually coaxially mounted onto an overhead shaft 11 and is preferably connected with a “stationary plug” 15a at one end and a “winding plug” 15b at the other end. Usually, stationary plugs 15a are connected to a fixed structure, such as for example, a support bracket 17 rigidly mounted to the wall. Winding plugs 15b are usually removably fixed to the overhead shaft 11 by means of suitable fasteners and are used to operatively connect the torsion spring 13 to the overhead shaft 11 so as to allow a torque transfer between the latter two.
FIGS. 2 and 3 show perspective views of stationary plugs 15a according to different embodiments of the prior art, and FIG. 4 shows a side view of stationary and winding plugs being shown cooperating respectively with an extremity of a torsion spring 13 mounted about an overhead shaft 11 of a counterbalancing mechanism 3 according to the prior art.
As is known in the art and as can be easily understood when referring to FIGS. 2–4, the ends of the torsion spring 13 are generally attached onto the plug 15 by either a) positioning a portion of the end of the torsion spring about the collar 19 of the plug and hooking a bent extremity of the spring 13 onto a corresponding hooking slot 21 of the plug 15, such as the one shown in FIG. 2, or b) by placing the plug 15 against the end of the spring 13 and screwing the threaded plug collar 19 into the spring, with a plug 15 such as the one shown in FIG. 3. This is particularly disadvantageous in that the above-mentioned way of connecting a conventional plug 15 onto a torsion spring 13 is relatively time-consuming, and very often requires substantial physical effort and/or specific tooling.
Also known in the art are the following U.S. patents and patent applications which describe various devices and methods for use with counterbalancing mechanisms of door assemblies:
U.S. Pat. No. 6,174,575 B1 (FOUCAULT et al.); U.S. Pat. No. 6,502,281 B2 (FOUCAULT et al.); U.S. Pat. No. 6,485,006 B1 (BEAUDOIN et al.); U.S. Pat. No. 6,327,744 B1 (DORMA); U.S. Pat. No. 6,263,541 B1 (SCATES); U.S. Pat. No. 6,174,575 B1 (FOUCAULT et al.); U.S. Pat. No. 6,134,835 (KRUPKE et al.); U.S. Pat. No. 6,125,582 (MONDRAGON et al.); U.S. Pat. No. 5,865,235 (KRUPKE et al.); U.S. Pat. No. 5,636,678 (CARPER et al.); U.S. Pat. No. 4,519,556 (TIMOSCHUK); 2003/0094248 A1 (MITCHELL); 2002/0043351 A1 (FOUCAULT et al.); 2001/0039761 A1 (SAVARD et al.).
None of the above-mentioned documents seems to describe a plug which by virtue of its design and components, enables to be installed quickly and easily onto the end portion of a torsion spring in a clip-like manner, so as to operatively connect the torsion spring onto a corresponding component of the counterbalancing mechanism, and thus enable a suitable torque transfer between the two via the plug.
Hence, in light of the aforementioned, there is a need for an improved device and/or method for operatively connecting a torsion spring onto a corresponding component of a counterbalancing mechanism, which would be able to overcome some of the aforementioned problems.